在Java中，将String数组转换为float数组的最快，最简单的方法是什么？

Question

I have something like this :

 String text[]="5.75,9.05,8.16,0.94,-0.10,-0.56,3.60".split(",");

And now I'm doing this to convert it to an array of float :

float f[]=new float[text.length];
for (int i=0;i<f.length;i++)
    f[i]=Float.parseFloat(text[i]);

I wonder if there is a one liner to do something like this :

float f[]=(float)text[] ?

Answer 1

In Java 8

Code :

    String text = "5.75,9.05,8.16,0.94,-0.10,-0.56,3.60 ";
    String[] spText = text.split(",");
    List<Float> list = Stream.of(spText)
            .map(f -> Float.parseFloat(f))
            .collect(Collectors.toList());

    list.forEach(f -> System.out.print(" " + f));

Output :

5.75 9.05 8.16 0.94 -0.1 -0.56 3.6

Explanation :

Stream class accept a array and you parse all String to float type one by one and you collect them in to a list which has type Float and print them out

One issue :

a String can be converted to an array of type String.

Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - incompatible types: java.lang.String cannot be converted to java.lang.String[]

Answer 2

Unless you're using Java 8, this is the fastest and easiest way to do what you need.

If you're using Java 8, you can do the following one liner:

Float f[] = Arrays.stream(text).map(t -> Float.parseFloat(t)).toArray(Float[]::new);

Answer 3

在Java 8中，您应该能够执行以下操作：

    float f[] = Arrays.stream(text).map(Float::parseFloat).toArray(Float[]::new);

Answer 4

First things first: while it is legal to declare an array using brackets after the variable's name, it is not recommended to do so. The following is the generally accepted way:

String[] text;

Also, I'm pretty sure you haven't ran your code through a compiler, since your syntax for creating your array isn't correct. The following is one of the correct ways to initialize an array:

String[] text = new String[]{"5.75", "9.05", "8.16", "0.94", "-0.10", "-0.56", "3.60"};

Now, to convert your String elements to float use the following:

String[] text = new String[]{"5.75", "9.05", "8.16", "0.94", "-0.10", "-0.56", "3.60"};
Float[] f = new Float[text.length];
Arrays.stream(text).map(Float::parseFloat).collect(Collectors.toList()).toArray(f);